Found something else yesterday after rabbitholing down the steam forums. Now you solved your problem already. But hopefully that keeps it from coming back.
Currently there seems the a problem with PowerTools installed and the Game.
So if the game is crashing after the Nvidia logo (on experimental or hotfix) try to remove PowerTools and restart the Steamdeck.
I have the same problem and actually tried to reset cryotools and set back UMA back to 1gb. Still no luck.
The only real difference I see is forcing experimental or hotfix. That atleast gets me to the Nvidia logo. Else it’s crash to homescreen directly.
I see that the game creates 2 crash logs and a crash dump in its Bin home folder when crashing. Sadly no easy helpful informations in there.
There was a new version of the original Myst for the iPad that was promoted recently. For sure hours of fun and headaches in that one.
Ali G indahouse